Alright, let's solve this problem step by step. We have 1402 and 9401 and we're adding them together.

Step 1: We'll start by adding the digits 2 & 1 in column 1 and get 3.

Step 2: We'll start by adding the digits 0 & 0 in column 2 and get 0.

Step 3: We'll start by adding the digits 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 1 & 9 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 1402 + 9401 = 10803.

